Refrigeration – Automatic control – Refrigeration producer
Patent
1998-10-26
2000-06-20
Wayner, William
Refrigeration
Automatic control
Refrigeration producer
62209, 62498, F25B 100
Patent
active
060763671
DESCRIPTION:
BRIEF SUMMARY
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
This invention has created without the sponsorship or funding of any federally sponsored research or development program.
1. Field of the Invention
This invention generally relates to the field of mechanical refrigeration and air conditioning and more particularly to improving efficiency of compression-type refrigeration and air conditioning systems.
2. Background of the Invention
In the operation of commercial freezers, refrigerators, air conditioners and other compression-type refrigeration systems, it is desirable to maximize refrigeration capacity while minimizing total energy consumption. Specifically, it is necessary to operate the systems at as low a compression ratio as possible without the loss of capacity that normally occurs when compressor compression ratios are reduced. This is accomplished by suppressing the formation of "flash gas" Flash gas is the spontaneous flashing or boiling of liquid refrigerant resulting from pressure losses in refrigeration system liquid refrigerant lines. Various techniques have been developed to eliminate flash gas. However, conventional methods for suppressing flash gas can substantially reduce system efficiency by increasing energy consumption.
FIG. 1 represents a conventional mechanical refrigeration system of the type typically used in a supermarket freezer. Specifically, compressor 10 compresses refrigerant vapor and discharges it through line 20 into condenser 11. Condenser 11 condenses the refrigerant vapors to the liquid state by removing heat aided by circulating fan 31. The liquid refrigerant next flows through line 21 into receiver 12. From receiver 12, the liquid refrigerant flows through line 22 to counter-flow heat exchanger (not shown). After passing through exchanger, the refrigerant flows via line 23 through thermostatic expansion valve 14. Valve 14 expands the liquid refrigerant to a lower pressure liquid which flows into and through evaporator 15 where it evaporates back into a vapor, absorbing heat. Valve 14 is connected to bulb 16 by capillary tube, 30. Bulb 16 throttles valve 14 to regulate temperatures produced in evaporator 15 by the flow of the refrigerant. Passing through evaporator 15, the expanded refrigerant absorbs heat returning to the vapor state aided by circulating fan 32. The refrigerant vapor then returns to compressor 10 through line 24.
In order to keep the refrigerant in a liquid state in the liquid line, the refrigerant pressure is typically maintained at a high level by keeping the refrigerant temperature at condenser 11 at a minimum of approximately 95.degree. F. This minimum condensing temperature maintains pressure levels in receiver 12 and thus the liquid lines 22 and 23 above the flash or boiling point of the refrigerant. At 95.degree. F. condensing temperature, this pressure for example would be; 125 PSI for refrigerant R12, 185 PSI for refrigerant R22 and 185 PSI for refrigerant R502. These temperature and pressure levels are sufficient to suppress flash gas formation in lines 22 and 23 but the conventional means of maintaining such levels by use of high compressor discharge pressures limits system efficiency.
Various means are used to maintain the temperature and pressure levels stated above. For example, FIG. 1 shows a fan unit 31 connected to sensor 17 in line 21. Controlled by sensor 17, fan unit 31 is responsive to condenser temperature or pressure and cycles on and off to regulate condenser heat dissipation. A pressure responsive bypass valve 18 in condenser output line 21 is also used to maintain pressure levels in receiver 12. Normally, valve 18 is set to enable a free flow of refrigerant from line 21a into line 21b. When the pressure at the output line of condenser 11 drops below a predetermined minimum, valve 18 operates to permit compressed refrigerant vapors from line 20 to flow through bypass line 20a into line 21b. The addition to vapor from line 20 into line 21b increases the pressure in receiver 12, line 22 and line 23, thereby suppressin
REFERENCES:
patent: 3081606 (1963-03-01), Brose et al.
patent: 5386700 (1995-02-01), Hyde
patent: 5749237 (1998-05-01), Sandofsky et al.
Sandofsky Marc D.
Ward David F.
JDM, Ltd.
Wayner William
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